1. Field of Invention
The present invention relates to a chemical-mechanical polishing (CMP) device. More particularly, the present invention relates to a chemical-mechanical polishing device with a porous dispensing tube.
2. Description of Related Art
In the manufacturing techniques of semiconductor devices, planarization surface is an important step in performing a high-density photolithography process. The planarized surface with little variation in height is easy to avoid the exposure diffusion and to achieve the precise pattern transfer. There are two major planarization techniques, Spin-On-Glass (SOG) and Chemical-Mechanical Polishing (CMP), however, in the sub-half-micron device era, the Spin-On-Glass method is incapable of providing required planarization and the Chemical-Mechanical Polishing method becomes the unique technique to provide global planarization on the manufacturing process of Very-Large Scale Integration; VLSI or even the Ultra-Large Scale Integration; ULSI circuitry.
FIGS. 1A and 1B are a top view and a side view showing a conventional chemical-mechanical polishing device, respectively. As shown in FIGS. 1A and 1B, the device includes a polishing table 10, a wafer holder 11 for wafer grabbing, a wafer 12, a polishing pad 13 over the polishing table 10, a tube 14 for carrying slurry 15 to the polishing pad 13, a liquid pump 16 for pumping slurry 15 to the tube 14, and a conditioner 17 for dressing the surface of the polishing pad 13. When the chemical-mechanical polishing device is running, the polishing table 10 and the wafer holder 11 spin independently along a certain directions, as depicted as the reference numbers 18a and 18b. The wafer holder 11 grabbing the back side 19 of the wafer 12, presses the front side 20 of the wafer 12 against onto the surface of the polishing pad 13. The liquid pump 16 also works continuously to pump slurry 15 to the polishing pad 13 through the tube 14. Therefore, the process of the chemical-mechanical polishing can rely on chemical reagents and abrasive particles suspended in the slurry 15. The reagents react chemically with molecules on the front side 20 of the wafer 12 to form an easy-grind layer, while the abrasive particles of the slurry 15 help to remove the protrusion within the easy-grind layer. Via the continuous chemical reaction and repeated mechanical abrasion, a surface of high planarity is ultimately formed over the front side 20 of the wafer 12. Basically, chemical-mechanical polishing is a technique of planarization, using the theory of mechanical polishing coupled with proper chemical reagents and abrasive particles to take off the fluctuated outline on the surface.
Polishing pad is a porous material, the cavities inside of the polishing pad could be stocked by the stuff used in the polishing process (such as abrasive particles of the slurry or something left during the process of wafer polishing) after using the polishing pad for a while, the performance of polishing may go down based on the changes of the characteristics of polishing materials. After a number of times of wafers polishing, the conditioner 17 would clean out the surface of polishing pad till the surface with cavities shows up. The polishing pad would not be renewed until the polishing pad could not be used anymore.
FIG. 2 is the bottom view of the conditioner, where on the rim of the main body 22 of conditioner 20 have a mounting pad 24 and each, is mounted with a plurality of diamond granules. The conditioners 20 use these diamond granules mounted on the polishing pad 24 to work when the chemical-mechanical polishing device is activated. However, these diamond granules could be nickel or the other kind of metal soldered on the mounting pad 24 of the conditioner 22. While the chemical-mechanical polishing device is running, any kind of acid or basic slurry (especially for those acid slurry used in metal polishing) may erode those solders between the diamond granules and mounting pads 24 to get separated off from the mounting pads 24 and to shorten the life of conditioner 22; also, those diamond granules left on the polishing pad may scratch the wafers in the process of polishing or later on to cause the destruction of devices.